FIG. 10 is a plan view illustrating a structure of a typical, conventional disk drive device 1 of the front-loading type. FIGS. 11(a)-11(c) are longitudinal sectional views illustrating the operations of the disk drive device 1. This disk drive device 1 primarily includes a disk transport mechanism 3 which transports an optical disk 2 from/to the inside of the disk drive device 1 to/from the outside of the disk drive device 1, a traversing mechanism 4 that will be described later, and a clamp mechanism 5. The optical disk 2 is DVD (Digital Versatile Disc) and CD (Compact Disc), for example.
FIG. 10 and FIG. 11(a) show a state in which the optical disk 2 is held so as to be rotatable (recordable and readable) inside the disk drive device 1. Information on the recording surface of the optical disk 2 is recorded and reproduced in the following sequential manner: the optical disk 2 is placed on a turntable 6 and sandwiched between the turntable 6 and the clamp mechanism 5 moving in concert at a predetermined recording/readout position, and then, the turntable 6 is rotated by a spindle motor 7, and the guide mechanism 8 moves an optical pickup 9 substantially in the radial direction of the optical disk 2 while bringing the optical pickup 9 closer to the recording surface of the optical disk 2.
The clamp mechanism 5 includes a clamper 5a and a stopper 5b. The clamper 5a includes: a clamp section 5c which sandwiches the optical disk 2 with the turntable 6 by magnetic absorption or the like; a connector section 5d connected to the clamp section 5c and having a small diameter; and a flange section 5e connected to the connector section 5d and having a large diameter. Meanwhile, the stopper 5b is provided with a hole 5f in which the connector section 5d moves freely. Therefore, as will be described later, depending upon the level of the optical disk 2 and the turntable 6, the optical disk 2 is clamped rotatably on the turntable 6 or is removed for loading and unloading operations.
In FIG. 10 and FIGS. 11(a)-11(c), the disk transport mechanism 3 is only represented by a tray. However, as will be described later, as illustrated in FIGS. 11(b) and 11(c), the disk transport mechanism 3 transports the optical disk 2 by horizontally moving the optical disk 2 placed on the tray from/to the recording/readout position illustrated in FIG. 11(a) to/from a loading slot 11 of a device main body 10.
Further, the traversing mechanism 4 includes: the turntable 6; the spindle motor 7 which rotates and drives the turntable 6; the guide mechanism 8; the optical pickup 9, provided on the guide mechanism 8, which is moved by the guide mechanism 8, a frame 12 having these components mounted thereon, and a drive source (not shown) which swings the frame 12. The frame 12 has a base end section extending outwardly beyond an outer diameter of the optical disk 2 and is supported so as to swing freely by an axis 12a which is parallel to the optical disk 2 and is orthogonal to a loading/unloading direction 13 of the optical disk 2. The frame 12 has the guide mechanism 8 and the pickup 9 provided to extend from the base end section of the frame 12, and the frame 12 has the spindle motor 7 which supports the turntable 6, provided at a free end section of the frame 12.
Therefore, when the frame 12 is risen by the drive source not shown, it goes into a recording/readout state illustrated in FIG. 11(a) where the turntable 6 lifts the disk 2 placed on the tray and the clamper 5a, and the optical disk 2 is sandwiched between the turntable 6 and clamp section 5c of the clamper 5a, thereby bringing about a state in which the optical disk 2 can rotate. On the other hand, in loading/unloading, the frame 12, as illustrated in FIG. 11(b), is lowered in the direction of an arrow 15, and the turntable 6 comes out of a table hole 14 which is provided on the tray. This places the optical disk 2 back on the tray. The clamper 5a is limited to move down by the flange section 5e and is separated from the optical disk 2. In this manner, the optical disk 2 can move in the loading/unloading direction 13.
FIGS. 12 and 13 are plan view and bottom plan view of the traversing mechanism 4, respectively. The guide mechanism 8 includes a rail 8a and a lead screw 8b on which the optical pickup 9 is provided, and a stepping motor 8c which is integral with the lead screw 8b. The optical pickup 9 is provided so as to hang across the rail 8a and the lead screw 8b in a pair. A movement piece 9a corresponding to the rail 8a can slide on the rail 8a. A movement piece 9b corresponding to the lead screw 8b is brought a driving force in the axis line direction of the lead screw 8b when the lead screw 8b is rotated by the stepping motor 8c. A pickup main body 9c containing an optical system, light receiving and emitting element, and others is supported between the movement pieces 9a and 9b. 
Referring to FIGS. 11(a)-11(c), the following will describe disk unloading operation of the disk drive device 1 arranged as described above. When the optical disk 2 is needed to be unloaded from the device main body 10, the spindle motor 7 starts a stop operation of its rotation soon, and the optical pickup 9 stops its signal reading/writing operation. Thereafter, the optical pickup 9 is moved by the stepping motor 8c of the traversing mechanism 4 in the center-of-rotation direction of the optical disk 2 (on the inner side in the radial direction of the optical disk 2; on the free end section side of the traversing mechanism 4), and holds in standby at the end-of-movement position close to the spindle motor 7, as illustrated in FIG. 11(a).
Subsequently, the traversing mechanism 4 starts lowering in the direction of the arrow 15, and the turntable 6 and the optical disk 2 also lower. At this moment, the clamper 5a starts lowering together with the optical disk 2 and the spindle motor 7 by adsorptivity of the clamp section 5c with respect to the turntable 6. When the clamper 5a lowers by the length of the connector section 5d, lowering of the clamper 5a is limited by the flange section 5e and the stopper 5b, whereby the clamper 5a terminates a clamp operation and releases the optical disk 2.
The released optical disk 2 still keeps lowering. However, as illustrated in FIG. 11(b), the optical disk 2 is caught by the tray of the disk transport mechanism 3 and held substantially in a horizontal state. The spindle motor 7 further lowers and stops at such a position so as not to interfere with the operation of the disk transport mechanism 3 that will be described later. This position is a position where the optical pickup 9 does not come into contact with the optical disk 2 held in the tray during a disk transport operation. The tray of the disk transport mechanism 3 is transported with the optical disk 2 placed thereon in an unloading direction 13a, as illustrated in FIG. 11(c), by a transport mechanism drive section (not shown).
Substantially reversing the procedure of the above operation, the optical disk 2 is loaded from the outside of the device main body 10 in the direction of an arrow 13b. Thus, for realization of the front loading, the traversing mechanism 4 is swung about the axis 12a as a swing support point to retract from a transport path of the optical disk 2, whereby it is possible to avoid a contact between the optical pickup 9 and the optical disk 2 at low cost, compared to an elevator mechanism.
Here, as another example of the conventional art given is Japanese Laid-Open Patent Application No. 1994/44633 (Tokukaihei 6-44633; published on Feb. 18, 1994). However, this conventional art relates to retraction of a bias unit in a so-called magnetically assisted optical disk device in which a bias coil unit and a writing optical head are used in pair. In most cases, the bias unit is used in such a state so as to substantially come into contact with a disk surface, and its action is basically a parallel movement. Therefore, the retraction by swing of an optical head like the present invention is not described at all. Especially, since optical media such as DVD and CD are recordable and readable only with a non-contact optical head (the foregoing optical pickup 9), only the optical head is retracted while keeping it from contact with a disk, thus realizing the reduction in thickness of the whole device.
In the above-mentioned conventional art, the optical disk 2 must be unloaded after the optical pickup 9 moves close to a position where the spindle motor 7 of the traversing mechanism 4 is mounted (to the end-of-movement position located on the inner side in the radial direction of the optical disk 2). This is because in the event that the optical disk 2 to be loaded and unloaded tilts, the optical pickup 9 which is closer to the turntable 6 on which the optical disk 2 is placed unlikely comes into contact with the optical disk 2. This means that the optical pickup 9 is at the farthest position from the axis 12a, which is an axis of swing of the traversing mechanism 4. Then, upon completion of lowering operation, a distance between the optical pickup 9 and the optical disk 2 maximizes, thus reliably avoiding the contact between the optical pickup 9 and the optical disk 2 at the time of loading and unloading of the optical disk 2.
However, in the above-mentioned disk drive device 1, to increase a distance between the optical pickup 9 and the optical disk 2 when lowering so as to reliably avoid the contact between the optical pickup 9 and the optical disk 2, the optical pickup 9 must be moved on the turntable 6 side which is on the free end section side of swing as described above. This arrangement maximizes the amount of swing of the optical pickup 9. However, generally the optical pickup 9 is greater in thickness than the combination of the turntable 6 and the spindle motor 7 which rotates the turntable 6, so that the optical pickup 9 is provided on the outer side of the spindle motor 7 in the radial direction of the optical disk 2, i.e. the optical pickup 9 is provided on the swing support point side. The thickness of the optical pickup 9 poses limitations to a thickness H1 of the whole device.
To reduce the thickness H1, the use of a thin optical pickup may be contemplated. However, the thin optical pickup is not usually used because it generally costs high, and the cost of the optical pickup makes up a high proportion of a total cost of the drive device. Meanwhile, a thin, wall-mount apparatus which is a flat and large monitor combined with periphery devices such as DVD, CD, amplifier, speaker, HDD, and tuner has recently become mainstream. Similarly, as to a disk drive device, a smaller thickness thereof becomes more important than a smaller occupied area thereof.